The present disclosure relates generally to implants, instrumentation, kits and methods for spinal surgery. More particularly, the present disclosure relates to expandable intervertebral body fusion devices for spinal surgery.
Back pain can be caused by several problems affecting the spinal vertebral discs, including, for example, degeneration, bulging, or herniating. The pain is attributable to friction or pressure that occurs when one or both vertebrae adjacent a disc exert uneven pressure on that disc, which can in turn irritate nearby nerve tissue. A typical remedy for a disc problem is to perform a cervical, thoracic or lumbar fusion (all generally referred to as “IF” herein) surgery utilizing an interbody or intervertebral implant. This type of surgery is intended to immobilize and ultimately fuse the two vertebrae on either side of the defective disc to form a single, solid bone mass.
Generally, in existing IF surgery, at least part of the defective disc is removed from the patient, the vertebrae are returned to their normal spacing, and a spinal implant device is inserted into that space to maintain the spacing and provide support to the adjacent vertebrae. The implant may be filled with bone graft material to promote fusion, and in certain instances, the intervertebral space may be provided with additional bone graft material.
Included among different types of intervertebral implants are expandable implants. Such implants often have an initially contracted configuration, such that they have a low profile in the superior-inferior direction, for ease of insertion into the intervertebral space. Such expandable implants can then be expanded in the superior-inferior direction after implantation, so as to securely engage and stabilize the vertebrae on both sides of the intervertebral space. Some such implants include mechanically locking mechanisms to lock the implant in the expanded configuration; however, these implants are difficult to manufacture, assemble, deploy and lock in situ. Moreover, should a surgeon determine the implant has been expanded too much or upon removal of the device in a revision, reduction in the height of such implants can often be difficult. Thus, there is a need for an expandable implant capable of easy in situ expansion and contraction.